/// <summary>
/// Determines whether the specified object, is equal to this instance.
/// </summary>
/// <param name="other">The other.</param>
/// <returns></returns>
public bool Equals(Change <TObject, TKey> other)
{
return(Reason.Equals(other.Reason) && EqualityComparer <TKey> .Default.Equals(Key, other.Key) &&
EqualityComparer <TObject> .Default.Equals(Current, other.Current));
}
/// <summary>
/// Removes the item from the specified index - intended for internal use only
/// </summary>
/// <param name="index"></param>
/// <param name="item"></param>
protected virtual void RemoveItem(int index, T item)
{
if (index < 0)
{
throw new ArgumentException($"{nameof(index)} cannot be negative");
}
if (index > _innerList.Count)
{
throw new ArgumentException($"{nameof(index)} cannot be greater than the size of the collection");
}
//attempt to batch updates as lists love to deal with ranges! (sorry if this code melts your mind)
var last = Last;
if (last.HasValue && last.Value.Reason == ListChangeReason.Remove)
{
//begin a new batch
var firstOfBatch = _changes.Count - 1;
var previousItem = last.Value.Item;
if (index == previousItem.CurrentIndex)
{
_changes[firstOfBatch] = new Change <T>(ListChangeReason.RemoveRange, new[] { previousItem.Current, item }, index);
}
else if (index == previousItem.CurrentIndex - 1)
{
//Nb: double check this one as it is the same as clause above. Can it be correct?
_changes[firstOfBatch] = new Change <T>(ListChangeReason.RemoveRange, new[] { item, previousItem.Current }, index);
}
else
{
_changes.Add(new Change <T>(ListChangeReason.Remove, item, index));
}
}
else if (last.HasValue && last.Value.Reason == ListChangeReason.RemoveRange)
{
//add to the end of the previous batch
var range = last.Value.Range;
if (range.Index == index)
{
//removed in order
range.Add(item);
}
else if (range.Index == index - 1)
{
_changes.Add(new Change <T>(ListChangeReason.Remove, item, index));
}
else if (range.Index == index + 1)
{
//removed in reverse order
range.Insert(0, item);
range.SetStartingIndex(index);
}
else
{
_changes.Add(new Change <T>(ListChangeReason.Remove, item, index));
}
}
else
{
//first remove, so cannot infer range
_changes.Add(new Change <T>(ListChangeReason.Remove, item, index));
}
_innerList.RemoveAt(index);
}
private static void Clone <T>(this IList <T> source, Change <T> item)
{
var changeAware = source as ChangeAwareList <T>;
switch (item.Reason)
{
case ListChangeReason.Add:
{
var change = item.Item;
var hasIndex = change.CurrentIndex >= 0;
if (hasIndex)
{
source.Insert(change.CurrentIndex, change.Current);
}
else
{
source.Add(change.Current);
}
break;
}
case ListChangeReason.AddRange:
{
source.AddOrInsertRange(item.Range, item.Range.Index);
break;
}
case ListChangeReason.Clear:
{
source.ClearOrRemoveMany(item);
break;
}
case ListChangeReason.Replace:
{
var change = item.Item;
if (change.CurrentIndex >= 0 && change.CurrentIndex == change.PreviousIndex)
{
source[change.CurrentIndex] = change.Current;
}
else
{
//is this best? or replace + move?
source.RemoveAt(change.PreviousIndex);
source.Insert(change.CurrentIndex, change.Current);
}
break;
}
case ListChangeReason.Refresh:
{
changeAware?.RefreshAt(item.Item.CurrentIndex);
break;
}
case ListChangeReason.Remove:
{
var change = item.Item;
bool hasIndex = change.CurrentIndex >= 0;
if (hasIndex)
{
source.RemoveAt(change.CurrentIndex);
}
else
{
source.Remove(change.Current);
}
break;
}
case ListChangeReason.RemoveRange:
{
//ignore this case because WhereReasonsAre removes the index [in which case call RemoveMany]
//if (item.Range.Index < 0)
// throw new UnspecifiedIndexException("ListChangeReason.RemoveRange should not have an index specified index");
if (item.Range.Index >= 0 && (source is IExtendedList <T> || source is List <T>))
{
source.RemoveRange(item.Range.Index, item.Range.Count);
}
else
{
source.RemoveMany(item.Range);
}
break;
}
case ListChangeReason.Moved:
{
var change = item.Item;
bool hasIndex = change.CurrentIndex >= 0;
if (!hasIndex)
{
throw new UnspecifiedIndexException("Cannot move as an index was not specified");
}
var extendedList = source as IExtendedList <T>;
var observableCollection = source as ObservableCollection <T>;
if (extendedList != null)
{
extendedList.Move(change.PreviousIndex, change.CurrentIndex);
}
else if (observableCollection != null)
{
observableCollection.Move(change.PreviousIndex, change.CurrentIndex);
}
else
{
//check this works whatever the index is
source.RemoveAt(change.PreviousIndex);
source.Insert(change.CurrentIndex, change.Current);
}
break;
}
}
}
/// <summary>
/// Inserts an item at the specified index
/// </summary>
/// <param name="index">the index where the item should be inserted</param>
/// <param name="item"></param>
protected virtual void InsertItem(int index, T item)
{
if (index < 0)
{
throw new ArgumentException($"{nameof(index)} cannot be negative");
}
if (index > _innerList.Count)
{
throw new ArgumentException($"{nameof(index)} cannot be greater than the size of the collection");
}
//attempt to batch updates as lists love to deal with ranges! (sorry if this code melts your mind)
var last = Last;
if (last.HasValue && last.Value.Reason == ListChangeReason.Add)
{
//begin a new batch if possible
var firstOfBatch = _changes.Count - 1;
var previousItem = last.Value.Item;
if (index == previousItem.CurrentIndex)
{
_changes[firstOfBatch] = new Change <T>(ListChangeReason.AddRange, new[] { item, previousItem.Current }, index);
}
else if (index == previousItem.CurrentIndex + 1)
{
_changes[firstOfBatch] = new Change <T>(ListChangeReason.AddRange, new[] { previousItem.Current, item }, previousItem.CurrentIndex);
}
else
{
_changes.Add(new Change <T>(ListChangeReason.Add, item, index));
}
}
else if (last.HasValue && last.Value.Reason == ListChangeReason.AddRange)
{
//check whether the new item is in the specified range
var range = last.Value.Range;
var minimum = Math.Max(range.Index - 1, 0);
var maximum = range.Index + range.Count;
var isPartOfRange = index >= minimum && index <= maximum;
if (!isPartOfRange)
{
_changes.Add(new Change <T>(ListChangeReason.Add, item, index));
}
else
{
var insertPosition = index - range.Index;
if (insertPosition < 0)
{
insertPosition = 0;
}
else if (insertPosition >= range.Count)
{
insertPosition = range.Count;
}
range.Insert(insertPosition, item);
if (index < range.Index)
{
range.SetStartingIndex(index);
}
}
}
else
{
//first add, so cannot infer range
_changes.Add(new Change <T>(ListChangeReason.Add, item, index));
}
//finally, add the item
_innerList.Insert(index, item);
}
/// <summary>
/// Adds the specified item.
/// </summary>
/// <param name="item">The item.</param>
public void Add(Change <TObject, TKey> item)
{
Add(item, false);
}
